Electric switch and contact structure



Oct. 13, 1931, T. T..GREENwooD A 1,827,430

ELECTRIC SWITCH VAND CONTACT STRUCTURE v Filed June'zg, 1929 Patentedoa. 13.219'31 UNITED STATES PATENT oFFlcE 'rama r. GREENWOOD, or usrrmrm'ron,

MASSACHUSETTS, ASSIGNOB TO CONDIT ELECTRICAL IANUFAUIUBING CORPORATION,OF SOUTH BOSTON, MASSACHUSETTS,

-A CORPORATION lOAF IABSACKUBETTS ELECTRIC AND' CONTACT STRUCTUREapplication fuga nuera-192s. sei-iai No. 374,837.

v loto point contact is obtained. Consequently,

the use of contact members presenting spheroidally formed confrontingcontact faces is advantageous, since the heat is more readily absorbedand dissipated from the contact surfaces and vaporization of the metalthereof is diminished. Current flowing through the conducting paths oftheswitch members is largely concentrated at the surfaces thereof, andconsequently where the current is concentrated at the center or tips ofthe contact `members'the U-shaped 'current path thus present sets up astrong repulsiveforce which acts against the contact members in a direc-.tion to force therebetween.v

It is an object of this invention to provide means to overcome thisrepulsive force set up by the natural current path through the contacts'and further to enhance th'e contact presso sure therebetween.

Another object is the provision of a contactsupporting solenold havingresilient convolutions which support one ofthe contact members, theconvolutions being attracted ytoward each other when heavy current flowsthrough them, whereby to press the contact member forcibly against the ycooperating contact member. A further object of the invention is theprothem apart and draw an arc 'rocable insulating switch rod 24 which is`the cooperating relatively fixed aroing con vision of means effectiveupon the tripping of p (ipe, o the relatively fixed contact members of1*`ig.,3 is a detail view showing diagrammatically the current paththrough a pair of coo erating contact members, the repulsive a tenl encyof which is overcome by the present invention.

As herein shown, the invention isincororated in a down break electricswitch havlng stationary switch members including the fixed conductingstuds 10 which are enclosed vin insulating bushings 12 and stationarycontact members 14 fixed to the lower ends of said'studs and providedwith lower contact faces 16 which comprise the fixed main contactmembers of the switch. lSaid main contact members 14 are furtherprovided with integral outstanding brackets 18 which are adapted tosupport the fixed auxiliary contact members hereinafter to be described.

The movable switch member includes a laminated, or brush, member 20having upwardly directed toe-sections 22 which engage the contact faces16 and a vertically recips, adapted to be connected with suitableoperat- 7 'ing mechanism Spot-shown) for opening and closing the switcin the usual manner: Said movable switch member is further provided witha rigid horizontal bridging member 26 which is adapted to carryremovably at its ends the upstanding auxiliary movable contact members28. f

In accordance with the present invention,

tact members 30 are adapted to be supported yieldingly on saidoutstanding brackets 18. f

To this end, said contactmembers 30 as here Y shown are provlded withupwardly extended conducting shank portions 32 which are disposedalongside and in the same vertical planefwith the switch studs 10. Saidshank portions 32 are screw threaded at their upper and lower endswhereby to carry the contact members 30 removably at the lower endsthereof. The upper screw threaded ends of said shank portions 32 arereceived in threaded apertures 36 at the upper ends of upstandingcylinders 38 which are carried removably by said outstanding brackets 18and up- 100 said cy f substanti 'said contact members 30 as well as anelectrically conducting solenoid series therewith. A sleeve 42 ofinsulatmg material is disposed about said conducting shank portions 32in the vicinity of the brackets 1.8 whereby to prevent contact betweensaid brackets 18 and said shank portions. A lock nut 43 is provided atthe extreme upper threaded end of said shank portions whereby to securethem fixedly at their upper ends in cylinders 38.

The cooperating arcm tips 28 and 30 are relatively massive where ylmorereadily to absorb and dissipate the eat enerated at the contact-faceswhen an arc is rawn therebetween. It has been found that sphericalcontacts, or contacts havin spheroidallyformed confronting contact aceswhich present a single point contact, are articularly advantageous inthis respect.- owever, the current path through a pair of such contacts,as indicated diagrammatically in Fig. 3, sets up a strong repulsiveforce due lto "the U- shaped current path in the vicini of the contacttips, as indicated at 44, which tends to force the contact members a artand cause a destructive arc to form there tween.

By the provision of the present invention, current passing throu h aswitch stud 10' before passin through t e auxiliary contacts 30 isoblige lto traverse the helical turns of the cylinder 38 which isdisposed about the shank portion 32 of the contact member andconsequently sets up a magnetic reaction bev tween the convolutionsthereof which tends to contract the convolutions of c linder v38 andconsequently to urge the relatively fixed arcing member 30 downwardlyinto engagement with its cooperating contact member 28.

It will be evident that the more current assed through the switch, thegreater wil be the force exerted against the contact member 28, which isheld against downward movement by a latch or other suitable deviceassociated with the switch operating mechanism, not shown. The shankportion 32 may be formed .of ma whereby to e ance the magnetic field andenhance the solenoid action of the convolutions of the cylinders 38.

A further advantage of this construction results, particularly when theswitch is opened on heavy overload, in the initial acceleration impartedto the movable switch member by the solenoid action of the fixed arcingcontact members. It will be obvious that this force operates toaccelerate the movable switch member before the separation of the arcingcontact members takes place so that a rapid movement of the switchmember formed slot or kerf extending' netizable material if desired 1 isattained prior to drawing the arc between gaged contact membersregardless of their configuration, so far as am now aware.

Itis old 'tovuse two mutually-attracted, unyielding contact supportingsolenoids to hold the contacts engaged, but in such case one solenoid,alone, is without effect. Care must ,be taken in the design of suchsolenoids, otherwise the attractive effect-between them will hold theswitch closed, regardless of efforts to open it. This cannot be the casewith the present invention.

The magnetic field of the ent in the arc zone of the auxiliary contactmembers so that the arc is caused to vrotate about the contactmembersand thus tol be the more rapidly extinguished.

The broad idea of utilizing a solenoid to rotate thecircuit-interrupting arc is disclosed and claimed in my copending aplicatiin Serial No. 755,353, iiled Decem 1 24.

solenoid is pres- Various modifications may be made in the' tconstruction and arrangement of the parts vwithout departing from thescope of the invention.

I claim:

1. An electric switch including the combination of la fixed currentconducting stud terminated in a maincontact block, a resilient solenoidhaving one end fixed to and electrically its other end free, anauxiliary contact member carried b the free end of said solenoid andvdisposed elow said main contact block, a

second and relatively unyieldindglyrsu portedauxiliary contact member amoved into enga ment with the contact member of said so enoid whereby toinclude said solenoid in the electric circuit including apte tobe saidauxiliary contact members, said sole-` noid adapted when traversed byheavy currents to Hex in a direction toward said second auxiliarycontact member and urge said auxiliary contact members into engagementby reason of the magnetic reactions the current traversing the turnsthereof.

2. An electric switch including a relativey rigidly supported contact, aresilient solefree, and a second contact member carried by said freeend, said solenoid arranged tol be included in the circuit through theswitch' and, due to the current. traversing it, to move the contactmember carried by the free end thereof toward said other contact member.

3. An electric switch including separable and exerts a force on one ofsaid arcing memconnected with said block and set up by.

los

. noid having one end fixed and its other end "niv bers to .urge it in adirection toward and against the other when traversed by. the switchcurrent.

4. An electric' switchincluding a contact, a resilient solenoid havingone end fixed and its other end free, and a second contact membercarried b said free and extended throu h said solenoi said solenoidarranged to .lie included in series with said contact member whereby tobe influenced by the current traversing the circuit to ile'x axially andmove its contact member into .pressure engagement with said other andcooperating contact member.

5. An electric switch including a contact, a resilient solenoid havingone end fixed and itsfother end free and a second contact membercarried'b)1 the free endof and extended through and insulated from theconvolutions' of said solenoid, said solenoid arranged to be included inseries with' the circuit through the switch whereby to be influenced bythe current traversing the circuit to alter its effective length andmove the contact member carried by its free end into engagement withsaid other and cooperating contact member.

6. An electric switch including the combination of a depending currentconducting stud terminated inl a main contact` block, a resilientsolenoid having one end fixed to and electrically connected with saidblock and 'tions of said soleno bracket, whereby to provide a currentpath havin its other end free for axial movement in a lrection parallelto the length of said stud, an auxiliary contact membercarried by thefreeend of said solenoid, a lcooperating relatively rigidly supportedcontact member adapted to be moved upwardly into a definite circuitclosing position in engagement with said first,contact member, theconvolutions of said solenoid being included in series with saidauxiliary contact members and adapted to be traversed by the currentthrough the switch and to be influenced therebyy to effect an axialmovement of its contact member into enga ement' with its cooperatingcontact mem r. I

7. electriclswitch including the combination of a fixed currentconducting stud terminated in a main contact block having, anoutstanding bracket, a resilient solenoid having one ende electricallyconnectedv with /said bracket and extended thereabove alongside saidstud, a contact member electrically connected with the free end of saidsolenoid and extended downwardly through the convolutions and insulatedfrom the convolu- 'd and also from said between said main contact blockand said auxiliary contact member which includes the convolutions ofsaid solenoid, a cooperating contact member movable upwardly into adeinite circuit closilg position wherein it is inl engagement with econtact member of said solenoid whereby to flex and lexpand said asupport for the and adapted to solenoid axially, said solenoid arrangedwhen traversed by an electric current to contract axially whereb to urgesaid contact meinbers in a direction to exert a pressure therebetween.v7

8. An electric `switch including the combination of a fixed conductingstud terminated in a main contact block, a resilient solenoid having oneend fixed to and electricall connected with said block and itsother enfree; 55 a pair of relatively separable auxiliary contact members one ofwhich isv rigidly supported and the other of which is carried by thefree end of said solenoid, said auxiliary contact members havinconfronting spheroi"- dally formed contact aces, means including theconvolutions of said solenoid to overcome the repulsive force resultingfrom the normal current paththrough said contact members to exert anopposin force" on the contactrliv member carried there y to urge itagainst the other and rigidly supported contact member.

,9. An electric switch i'ncluding'thev combination of a pair ofcooperating contact members having confronting spheroidallyo formedcontact faces, one of which contact members is rigidly supported, andmeans including a resilient solenoid which constitutes other contactmember in.- cludedin series with said contact members-.$5 and arrangedto be deformed bythe magnetic reaction of the currentpassingtherevthrough toexert a force on the contact member carriedthereby urging itinto engagement with said other and rigidly supportedoocontact member.

10. An electric switch including a. currentcontractible solenoid havinga-ixed end and a movable end, a contact member carried by said movableend, and 'a second contact memselos ber cooperatingv therewith, saidsolenoid. being included in series with said contact member and arrangedto contract by the current traversing it to urge its contact memberagainst the other contact member. :511e

l1. An electric switch including a current- Icontractible solenoidhavinglavixed end and a movable end, a contact member carried by saidmovable end, and a second contact member cooperating therewith, saidsolenoidvbell! ing included in series with said contact member andarranged to contract by the currentl traversing it to urge its contactmember against the other contact member, said solenoid also constitutingmeans to rotate thei. circuit-interruptin arc between said separatedcontact mem rs. 1

12. An electric switch having; separable contact members, and,afsolenoid in series therewith providing ,a 'su port v:for one-0h12!them having s aced yiel ingv convolutions contracted axially to urge itscontact member against the other contact f merpber when traversed by-theswitchl curlen ,A .A I Y I' 13. An electric switch having separablecontact members, and a solenoid in series therewith rovidinga su portfor one of them, having s aced yiel mg Yconvolutions and adapted tocontracted axially to urge its contact member against the other contactmember when traversed by the switch current, said solenoid alsoconstituting means t'o rotate the circuit-interruptin 'arc between saidseparated contact mem rs.

14. An electric switch having separable contact members, a solenoidhavin yielding convolutions in series therewitg and a fixed end and afree end which is attracted toward said fixed end by the currenttraversing the convolutions, and means connect' one of saidl contactmembers with said free end so lthat said contact members will beurged-against each other by the contraction of the solenoid.

15. An electric switch having separable contact members, a solenoidhaving yielding 'convolutions in series therewith and a fixed end and afree end which is attracted toward said fixed end by the currenttraversing the convolutions, and means connecting one of said contactmembers with said free end so that said contact member will be urged"against each other by the contraction ofthe solenoid, said solenoid alsoconstituting means to rotate the circuit-interrupting larc between theseparated contact members.

16. An electric switch having separable contact members, a solenoid inseries therewith h ving spaced convolutions which are free to attractedtoward each other and to contract the solenoid by the current traversingthem, supporting means, for one end of the solenoid, and meansconnecting a contact member with the other end of said solenoidv bywhich such contact lmember is urged against said other contact member bythe contraction of said solenoid.

17. An electric switch having cooperating fixed and movable contact'members, a solenoid located thereabove having a fixed lower end and amovable upper end and connected in series with said contact members andhaving spaced convolutions which are attracted toward each other by thecurrent traversing the solenoid, thereby to move the upper end thereofdownwardly, and means lconnecting one of said contact members with saidupper end .arranged to press said contact members together by thecontraction of said solenoid.

18. An electric switch having cooperating fixed and movable contactmembers, a solenoid located thereabove having a fixed-lower end and amovable upper end and connected in series with said contact members andhaving spaced convolutions which are attracted toward each other by thecurrent traversing the solenoid, thereby to move the upper end thereofdownwardly, and means connecting -one of said contact members with saiduprod which f noid,

` and having psr end arranged to press said contact memrs together y thecontraction of said solenoid, said means including a rigid conductpasses.upwardly withinV said 19. An electric switch having cooperatin fixedand movable contact members, a solenoi located thereabove havin a fixedlower end and a movable upper end and connected in series with saidcontact members and hav' spaced convolutions which are attracted towardeach other by the current traversin the solenoid, thereby to move theupper end thereof downwardly, and means connecting one of said contactmembers with said u per end, arranged to prem said contact memerstogether bythe contraction of said solenoid said means includin a rigidconducting rod which passes upwa ly wlthin said solenoid, and iscomposed of ma etizable material.

20. An electric switc having cooperating fixed and movable contactmembers, a solenoid located thereabove having a fixed lower end and amovable upper end and connected in series with said contact members andhaving spaced convolutions which are attracted toward each other by thecurrent traversin the solenoid, thereby to move the upper end thereofdownwardl and means connecting one of said contact members .with saidupper end arranged to press said contact members together by thecontraction of said solenoid, sald solenoid also constituting aresilient support for its contact member.

21. An electric switch having cooperating fixed and movable contactmembers, a solenoid located thereabove having a fixed lower end and amovable upper end and connected in series with said contact members andhaving spaced convolutions which are attracted toward each other by thecurrent traversin the solenoid, thereby to move the upper enthereof-downwardl and means connecting one of said contact members withsaid u per end arranged to press said contact mem ers together by thecontraction of said solenoid, said solenoid also constituting aresilient support for its contact member and also means to rotate thecircuit-interrupting arc between said contact members.

22. An electric switch having a support, a resilient solenoid havingaxially-spaced convolutions fixed at its lower end to said support anupper end which is free to move toward said fixed end by the attractiveeffect of the current traversing theconvolutions, a stud connectedmechanically and also electricall with said free end and extendeddownwar ly therein, a contact member carried by the lower end of saidstud, and a movable contact member dis osed below and cooperating withsaid fixed) contact member.

Y 23. An electric switch havin a fixed contact member, a relatively rigily supported movable contact member cooperating therellO with andmovable into a definite switch closed position, and a spiral compressionspring yieldably supporting said fixed contact member, whereby it canmove while engaged by said movable contact member, said spring beingelectrically in series with said contact members and including means tourgeits contact member into engagement with said cooperating contactmember when traversed by the switch current.

24. An electric switch having separable contact members, a support ofmagnetizable material for one of said contact members, and means tomagnetize said support including a solenoid which also providesl ayielding support for said contactsupport.

25. An electric switch khaving separable contact members, a support ofmagnetizable material for one of said contact members, and means tomagnetize said support by the current traversing said contact members.including a solenoid which also provides a yielding support for saidcontact support.

26. An electric switch including separable contact members havingengageable contact faces, a magnetizable support for one of said contactmembers extended thereintoand terminated adjacent the contact facethereof, and means to magnetize said support including a resilientsolenoid which is fixed at one end and carries said magnetizable supportat its free end.

27. An electric switch including separable I contact members havingengageable contact faces, a magnetizable support for one lof saidcontact members extended thereinto and terminated adjacent the' contactface thereof, and means to magnetize said support including a windingwhich surrounds said support andhis `connected electrically in seriestherewit 28. lAn electric switch including the combination of a pair ofcooperating contact members, and means included electrically in serieswith said contact members and constituting a support for one of themwhich actsv to urgeits contact member by electromagnetic forces due tocurrent traversing the yswitch into engagementwith its cooperating fcontact member and which also acts to set up a'magnetic field which actsradially of the line of separation of said contact members whereby torotate'the circuit` interrupting arc drawn therebetween.

VIn testimony whereof, I have signed my name to this s ecification.

TLMA. T. GREENWOOD.

